If there's "sludge" or green coolant in your oil then that is bad. Most likely a leaking head gasket. I hope it doesn't look as bad as this.

 

Holy crap! What did that come out of?

 

That is oil/water emulsion i was talking about. If I had said it looks like baby poop it might have provided a better visual for you. Yep, that's a lot of water.

 

Man, I hate to be the bearer of bad news but you are about to have a head gasket blow. This is exactly what my oil cap looked like last week and then Monday...ka blewwwy.

Are you adding coolant about every 3 weeks? I was losing a small amount of coolant such that about every 3 weeks I would have to replace about a gallon. It was not appearing as a leak anywhere, nor was I finding an emulsion when I changed the oil or checked the oil...

The only sign was this emulsion on the inside of the cap and oil filler spout.

My problem went on for about 10 months...losing coolant with no discernable leakage...then last Monday, I went to fill it up while the engine was running and after some head pressure had built up and that resulted in the final failure.

The engine never overheated, but when I got home, I checked the dipstick and sure enough...emulsified oil. I then drained the pan and had about a half gallon of water mixed with my 5 quarts of oil...so now I get to replace my head gasket.

Also a word of warning...I have no quantitative data only a suspicion after 3 head gaskets on two vehicles....STAY AWAY from Synthetic OIL. I swear that as the engine ages and the tolerances get a little looser...synthetic oil is so slick it works its way in between the gasket and causes the failure.

 

well, i have not added any coolant basically since '01.

i checked inside the cover and everything is clean as a whistle... i'm going to keep my eye on it, but for the moment write it off to condensation.